This invention relates to closure caps such as screw caps and crown caps for the closure of glass containers, such as bottles, flasks, and the like, and more particularly it relates to the gaskets for use in such caps in order to provide a tight seal even at a rather high pressure in a glass container, such as it would be the case with bottles containing gas saturated liquids, such as beer or soft drinks.
The gasket according to the invention is made from a plastics foil, particularly a polyethylene or polypropylene foil, in form of a pan-shaped element comprising a disc portion, a skirt depending from the disc portion, and a peripheral flange extending outwardly from the skirt of the gasket.
According to a main feature of the invention, the skirt of the gasket is folded, upon applying the cap on the container to be closed, into a bellows-like manner between the cap bottom and the rim of the container, thus providing a very efficient seal through a simple change in its shape, without any deformation of the material of which it is made, which seal is assured with a much lower cap tightening or clamping pressure than that required for prior art gaskets.
This invention is also concerned with a method of manufacturing the above mentioned gaskets.
Further objects and advantages of the invention will be apparent from the following description of the preferred embodiment of the gasket according to the invention and of the method for manufacturing it, made with reference to the accompanying drawings.